1. Field of the Invention
The present invention relates to the field of data processing systems. More particularly, this invention relates to a data processing system arranged to receive a source trace data stream corresponding to a source trace protocol and to supply the received trace data to trace accepting circuitry
2. Description of the Prior Art
Many known data processing systems comprise trace data generating mechanisms. Examples of such systems are the Embedded Trace Macrocell designed by ARM Limited of Cambridge, England. Such trace mechanisms serve to monitor the data processing operations taking place on a data processing apparatus and to generate a trace data stream indicative of the data processing operations occurring, such as which instructions are being executed, and which data values are being manipulated. This source trace data stream is typically output (possibly after on-chip buffering) to trace data analysing circuitry such as a software diagnostic tool to assist a hardware designer or a programmer in debugging the data processing system.
As data processing systems increase in complexity, it is becoming common to use System-on-chip (SOC) designs that typically contain many different data processing elements, each performing its own data processing operations in communication with other data processing elements. As an example, a single integrated circuit may include a processor core, a digital signal processor and a memory system. Each of these elements can be separately subject to tracing and can generate its own individual trace data stream. Each of these plurality of trace data streams can potentially have a respective different trace protocol according to which the trace data is formatted. Providing separate trace mechanisms for each trace data source can disadvantageously consume pin count and separate inputs and outputs  need to be provided for each trace data source. Accordingly, it is desirable in data processing systems comprising a plurality of trace data sources to generate a combined trace data stream comprising trace data from a plurality of trace data sources. This can present a difficulty since different source trace protocols associated with a different trace data sources may have different and incompatible trace data formats
Furthermore, even in a data processing system comprising a single trace data source, it may be required to supply a source data stream to trace accepting circuitry for further analysis and the trace accepting circuitry may be configured to accept trace data in a predetermined format that is incompatible with the format specified by the source trace protocol. Accordingly, there is a requirement for a data processing system that enables trace data to be output for analysis in a more flexible format.